Electron discharge device of the magnetron type



March 9, 1948. P. 1.. SPENCER I 2,437,230

ELECTRCN DISCHARGE DEVICE OF THE MAGNETRON TYPE- Filed Nov. 2, 1945 '2 sheets-sheet 1 INVENTORQ fzlvcy ,4. d m cm,

March 9, 1948. p, SPENCER 2,437,280

ELECTRON DISCHARGE DEVICE OF THE MAGNETRON TYPE Filed Nov. 2, 1945 2 Sheets-Sheet 2 IN VEN TOR.

- P5170 l. SPEWGf/f,

Patented Mar. 9, 1948 LECTR N HARGE D I 1? THE.

' MAQNEfmoN-TYPE Percyt L. Spencer; West Newton, Mass assig nor; to Raytheon Manufacturing Gompany, Newton, .mcornpratim D laware.

A plicatipn n ve p i- 2, 19 43; Serial No. 508.709

' some (crews-.39.)

This inventionrelates toa magnetron,- and more particularly to oneof the multiple anode type in whichthe internal structure providesa a plurality-of oscillating circuits,- alL of whicharei intended to oscillate at the same frequency and thus to contribute tothe effective output of the" magnetron. Heretofore: difficulty has-been. en-.' countered in coupling au'Of t/hBioscillating.cir-. cuits together, and propagating the oscillatory energy from circuitto circuit untilit ispicked up by the output-connection I believelthisehas. been .due to thef act that such couplinghas her-ea toforebeen:accomplished throughacomplenand elongatedpath'. 1 a

An object of: thisiinvention. is'ito-deviseiaimage l.- The.anode.arm.members 5 may be formedby.

" being. stamped from a sheet. of highly. conductive.

copper. Each. of; said. anode arm. members is. formed-witha centralopening Sand is. divided; along'one side to provide upper and lower. anode. arms 1; and; 8'. Each anode arm. member. 5 is. thenbent. seas-to displace. the: arms I and-18' relatively to each. other-.. The anode. arm.mem-. hers 5 ar-esoarranged-within the. envelope. I that theupperfiandlower; anode. arms, 1 and 8, are

alternately disposed around the. central region.

netronof the foregoingtypeinawhich thecoupling. 1

between the oscillating. circuits. is. accomplished:

by a simple pathof shortenedflength.

Anotherobject is-toadevise:. an. arrangementin;

which. the. coupling. between the. oscillatingapon-l oxides; andrhaving. an internal heater.

tion of the deviceiandsthe.output;means;issube stantially increased:

A further object isltoz devise an. arrangementeof the: above. type in. whichethe. efiiciency. thereof: is:- substantially increased;

The foregoing andiother objects .ofQthis. invene.

Fig. 3 is aperspective view.'of;one.of.- thezanoda arm members-.019thearrangement shownin; Figs. L and 2;.

Fig. 4; is a. longitudinal. cross-section, similanv to Fig. 1 of another embodiment.ofzmyinyention;z

and i Fig.- 5 is-a perspective viewoione. ofzthe-anode arm members of the arrangement; shown. in;

Fig. 4.

The magnetron illustratedsin'figs. 1. and.2;com.-. prises a tubular envelope lmadeiof a'. cylinder- 0f conducting material, such asoopper; The. ends; of the envelope are covered-by capsi and 3 like). wise formed of' conducting material,- such as; copper, and hermetically soldered in place on;the: ends ofenvelope I. The envelope 1' is formed with a-centralannularproje'ctionA-Q A plurality: of anode arm members! are secured tothe innen face of the projection 4, as by soldering-and dist posed substantiallyradially' within' the -envelope withintheenvelope. l. The. outer edges of the. arms 1' and. 8iformelectron. receiving. j anode f aces. whichcooperatewith .a cathode .supported;subjstantiallybentrally of." said. anode. faces. The cathode: 9. is. preferably of: the. indirectly heated oxide-coated) thermionic type. having an outer conducting-cylinder coated withelectron emissive The end conductors [ill and iii; of. the heate project from the' opposite ends; of; the cathode. structure. 9; O'nmofr the. conductors Ill may be electrically. connected to theexternal. cathodesleeve, whil another. conductor' L1; is insulated from said; sleeve. Thecathode-Q iss ppQrted by a pair ng lead-in conductors l2 weldedrespectivelyrto the; end conductors l0, and I1. The lead-in conductors: I 2, pas -throu heles is a s. 3 mQ ntet the: outer. ehdso on ct g. nines l he me wally. sealed throu h th wal of. t e. nve ope; adjacentthe upper and lower ends thereof.

Whenuch. a ma ne ron a e b e n. suitablemaeneti Po es; '5: r ete ong tu na magnetic field and. the; device, is: energized, o sci l-. lations; are-set; up; l ega oscillations may be; led out. f-romthetubeby. means oi a coupling loop 1 6 substantia l ali ned with. he; Open n s the de rm members 5:, Q e-end f; h co in loop. I6 is. connectedto the inner end: of a con; ducting pipe I]: hermetically sealedthrough the wall ofthe envelope I s bsta ti l dw be: tween the endsgthereof... The other end of -the coupling: loop I6; is connected. toa conductor I 8; h ch asses th ou h s d pipe and: s se led. through a glass; seal IQmountedat theouter en d ofisaid p p An add ti n l condu t n pi e, not show.n,.may:- be electric ll connect d: o he ipe: H: andsiorm with: the conductor It; a concentric: transmission line throu h which the high {re quency. oscillations. generatedby the; magnetron may be. led to a suitable utilization device.

n'the abovecon truct qn e1 apacitanc ist b' twe nadiacent anode arms-p Likew s a. 9 ducting path exists between, each pairof alt hate ej' m r. te dip iior amn e, fr m;

portion of said adjacent arm member to the lower anode arm 8 thereof. Each of the above disposed paths contains a substantial amount of inductance.

It is desired that all of these circuits shall be resonant at a definite predetermined frequency at which the device is to be operated. When the magnetron is in its oscillating condition the anode arms 7 and 8 will be of opposite voltage phase, and thus oscillating currents will flow through each of the conducting paths above described. These oscillating currents will flow in a generally circular direction around each opening 6 and thus tend to create a magnetic field extending axially through each of said openings. It will be noted that the openings 6 collectively form a closed annular space within the envelope I. Since the anode arms 1 and 8 are of opposite voltage phase all of the oscillating currents will be in phase so as to tend to create an annular magnetic field extending in one direction through said annular space during one half cycle and in the other direction through'said annular space during the other half cycle. Thus all of the oscillating currents will contribute to the production of a strong resultant annular magnetic field in said annular space. The coupling loop i6 is interposed so that said resultant magnetic field passes through said coupling loop whereby said loop is closely coupled to all of the oscillating circuits. In this way the energy of each of said oscillating circuits is propagated through a simple annular path of shortened length directly to said coupling loop l6, which thus leads said oscillatory energy from the tube with a substantial maximum of efficiency.

' The close coupling between all of the oscillating circuits tends to force all of said circuits to.

oscillate at exactly the same frequency even though slight differences in the natural frequencies'of said circuits might otherwise tend to exist. Also sucha-construction has a strong tendency to eliminate the probability of the tube to oscillate in various spuriousmodes which in previous devices have substantially decreased the efiiciency. Tubes constructed as above therefore tend to be of a substantially increased efficiency.

Instead of the arms I and 8 extending only to the central portion of the tube, the device could be made so that these arms would extend substantially the full length ofthe cathode, thus utilizing the cathode emission in a more completely effective manner. Such an alternative construction is shown, for example, in Figs. 4 and 5. In these figures the same reference numerals which are used in Figs. 1-.-3 are applied where the elements are identical. The anode arm members of Figs. 1-3 are replaced by the anode arm members shown most clearly in Fig. 5. These members are likewise each formed with a central opening 24 and upper and lower anode arms 22 and 23 displaced'from each other in the same manner as described in connection with anode arms 1 and 3. However, the anode arms 22 and The above capacitances and inductances constitute a plurality of tuned circuits.

4 venient way of forming such an anode arm member is to make it in two halves, each stamped out of a sheet of copper, and after bending each half in the desired direction said halves may be joined by soldering along a joint indicated at 24 in The embodiment illustrated in Figs. 4 and 5 operates substantially identically with the opera- 1 tion as described in connection with Figs. 1-3.

. Of course it is to be understood that this invention is not limited to the particular details as described above as many equivalents will suggest themselves to. those skilled in the art.

' What is claimed is:

cathode, an anode structure, said anode structure '1. An electron discharge device comprising a comprising a plurality of anode arm members each having a pair of electron-receiving faces adjacent said cathode, each pair of said faces being interconnected through a path of conducting material in its arm member, said path surrounding an opening in said arm member, said arm members being disposed with said openings substantially in register and defining a resultant path in which a resultant magnetic field is adapted to be set up, and a coupling loop interposed in said resultant path.

2. An electron discharge device comprising an elongated cathode and an anode structure, said anode structure comprising a plurality of anode arm members each having a pair of elongated electron-receiving faces adjacent said cathode, said anode arm members being disposed substani tially parallel with and around said cathode, each pair of said faces being interconnected through a path of conducting material in its arm member, said path surrounding an opening in said arm member, said arm members being disposed with said openings which substantially in register and '1 of said faces being interconnected through a path of conducting materialin its arm member, said path surrounding an opening in said arm member, said arm members being disposed with said openings substantially in register and defining a resultant annular path in which a resultant magnetic field i'sadapted' to be set up, and a coupling loop interposed in said annular path.

4. An electron discharge device comprising a cathode and a plurality of conducting plates mounted in generally'radial directions around said cathode, each of said plates having an opening therein and having 'a pair of anode arms extending in opposite directions along one side of said opening, said arms being displaced, from each other in a direction transverse to said plate.

5. An electron discharge device comprising a cathode and a plurality of conducting plates mounted in generally radial directions aroundsaid cathode, each ofv said plates having an opening therein and being divided at one side of said 23 extend, respectively, substantially the full opening forming a pair of anode arms extending in opposite directions, said arms being displaced from each other in a direction transverse to said plate.

6. An electron discharge device comprising a cathode, a plurality of conducting plates mount ed in generally radial directions around said cathode, each of said plates having an openin therein, and having a pair of anode arms extending in opposite directions along one side of said opening, said arms being displaced from each other in a direction transverse to said plate, said openings being registered and defining a resultant annular path, and a coupling loop interposed insaid annular path.

7. An electron discharge device comprising a cathode, a plurality of conducting plates mounted in generally radial directions around said cathode, each of said plates having an opening therein, and having a pair of anode arms extending in opposite directions along one side of said opening, said arms being displaced from each other in a direction transverse to said plate, each of said arms being of substantially the length of said plate.

8. A magnetron comprising a cathode, a plurality of conducting plates mounted in generally radial directions around said cathode, each of REFERENCES CITED- I The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,123,728 Hollmann July 12, 1938 2,250,698 Berline July 29, 1941 2,199,177 Hollmann Apr. 30, 1940 2,084,867 Prinz et al June 22, 1937 2,005,793 Lindenblad June 25, 1935 Certificate of Correction Patent No. 2,437,280. March 9, 1948.

PERCY L. SPENCER It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 4, line 39, claim 2, strike out the word which; and that the said Letters Patent should be read with this gilt-{action therein that the same may conform to the record of the case in the Patent Signed and sealed this 4th day of May, A. D. 1948.

THOMAS F. MURPHY,

Assistant Uommissioner of Patents. 

